In recent years, due to the spread of hybrid cars and the like, electric wires, connectors, and the like, which are automobile components, have been required to be highly voltage resistant and highly heat resistant. Conventionally, a crosslinked vinyl chloride resin electric wire or a crosslinked polyolefin electric wire has been used as an insulated electric wire used in a place having a high temperature, such as a wire harness of an automobile and the like. Electron beam crosslinking has mainly been used as the method for crosslinking these insulated electric wires (for example, see JP 2000-294039A Patent Document 1).
However, there has been a problem in that electron beam crosslinking requires an expensive electron beam crosslinking apparatus and the like, and high equipment cost, and thus manufacturing cost increases. In view of this, silane crosslinking, with which crosslinking is possible with inexpensive equipment, has been receiving attention. A polyolefin composition is known which is used in a coating material for an electric wire, a cable, and the like and can be subjected to silane crosslinking (for example, see JP 2000-212291A and JP 2006-131720A Patent Documents 2 and 3).